Field of the Invention
The present invention relates to a liquid crystal display device, a color filter substrate and a method for producing the color filter substrate.
Discussion of the Background
Efforts for reducing the weight of electronic equipment, including liquid crystal display devices, have been made. For example, liquid crystal display devices are included in information devices such as cellular phones or portable computers. As an example for operating the information devices, for example, a technique for inputting directly to liquid crystal display surfaces with fingers, pointers or the like is employed.
Direct input methods to liquid crystal display surfaces include an on-cell method. In the on-cell method, a touch panel having a sensing function is provided on a front surface of a liquid crystal panel, and the touch panel receives input. Also, direct input methods to liquid crystal display surfaces include an in-cell method. In the in-cell method, a matrix of sensors having a sensing function is disposed in an array substrate or a counter substrate of a liquid crystal display device, and the sensors are provided inside a liquid crystal cell.
As an example of techniques employed in on-cell methods, PTL1 (Japanese Patent Application Publication No. H10-171599) has disclosed touch panels of a resistive film type, electromagnetic induction type, electrostatic capacitive type and optical type.
However, in on-cell methods where touch panels are provided on the liquid crystal display surfaces, the thickness and weight of the touch panels are added to the liquid crystal display devices, which causes increase in thickness and weight. Further, light reflection from top surfaces of touch panels and inner surfaces of touch panels sometimes lowers quality of liquid crystal display.
In contrast, in in-cell methods where sensors are provided inside liquid crystal cells, thicknesses of liquid crystal display devices do not increase, and display quality is unlikely to lower. Accordingly, in-cell methods are preferably used. As an example of sensors having a sensing function, light sensors have been developed.
In liquid crystal display devices used in electronic equipment or information devices, stereoscopic image display tends to be used. Regarding stereoscopic image display by liquid crystal display devices, technical requirements have increased. For example, there is a need for a click feeling to buttons displayed stereoscopically. For example, input with fingers needs prevention of incorrect operation.
If liquid crystal panels include light sensors, in order to prevent false detection from occurring because of effects of temperature or backlight sources, there is sometimes a need for compensating results detected by the light sensors.
As an example of sensors, silicon photodiodes are used, the silicon photodiodes having channel layers containing polysilicon or amorphous silicon. The silicon photodiodes generate dark current due to changes in such as ambient temperature. This may cause noise, which is not observed light, to be added to observed data.
PTL2 (Japanese Patent Application Publication No. 2002-335454) and PTL3 (Japanese Patent Application Publication No. 2007-18458) have disclosed that operational compensation is performed using a photodiode that corrects the dark current. In PTL2 and PTL3, imaging elements compensate the dark current.
PTL4 (Japanese Patent Application Publication No. 2009-151039) has disclosed a technique where the S/N ratio of detected signals is improved by operation using signals of a first light receiving element and signals of a second light receiving element. However, this PTL4 has not disclosed a technique for color-separating visible light accurately. The display device of PTL4 (Claim 1) includes an optical filter disposed on the first light receiving element and absorbing light in a visible light region. Further, the display device of PTL4 includes a light-shielding portion that absorbs/shields incident light.
However, color-separation of blue light, green light and red light is not suggested or mentioned in the PTL4. Further, PTL4 has not disclosed an alignment method for producing color filter substrates. PTL4 (paragraph [0013]) has disclosed touch sensing where a noise component is cancelled.
PTL5 (Japanese Patent Application Publication No. 2010-186997) and PTL6 (Japanese Patent Application Publication No. 2011-118888) have disclosed light sensors (light receiving elements) made of oxide semiconductors. PTL5 has disclosed a light sensor employed in displays using mainly organic substances as emission layers. PTL6 has disclosed a display device having, in addition to a light sensor as an area sensor, another light sensor for position detection. PTL7 (Japanese Patent Application Publication No. 2011-065133) has disclosed a liquid crystal display device having a light sensor for short wavelengths, a light sensor for red and a light sensor for infrared light.
PTL1: Japanese Patent Application Laid Open Publication No. H10-171599
PTL2: Japanese Patent Application Laid Open Publication No. 2002-335454
PTL3: Japanese Patent Application Laid Open Publication No. 2007-18458
PTL4: Japanese Patent Application Laid Open Publication No. 2009-151039
PTL5: Japanese Patent Application Laid Open Publication No. 2010-186997
PTL6: Japanese Patent Application Laid Open Publication No. 2011-118888
PTL7: Japanese Patent Application Laid Open Publication No. 2011-065133